Raspberry Pi 5 (bcm2712) or Pi 4B (bcm2711) for L4S Build Notes (Sept 23, 2024)

This is not an endorsement of L4S but the expected use is for technical evaluations.

Help towards building a kernel which is L4S capable, dual queue and runs on a raspberry pi 4 or 5 (5 is higher performing and can drive 2.5G USB ethernet.) These devices can also be used as a dual queue L4S marking plane. (per the use of iproute2) The devices are assumed to be used for experimental, wired & wireless testing purposes and not on production networks.

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Hardware requirements & suggestions

Software

Other

Native build with apt (build from source notes here)

Create a full debian bullseye system with 64 bit support, using a 64G micro SD card

  1. Download the bullseye image from here or from debian.

  2. Use rasberry pi imager to write to a 64G card, it will destroy all existing data

  3. Install the card into a raspberry pi 4 with wired ethernet attached

  4. Boot card and follow initial setup including creating a user id, and system updates

  5. Reboot, set root password with ‘sudo passwd’

  6. optionally ‘sudo apt-get install firefox-esr’

  7. optionally enable ssh via ‘systemctl start ssh” & ‘systemctl enable ssh’

  8. Install build tools

Build a L4S capable kernel (not optimized)

  1. Clone the kernel from l4s team site
  2. Get the sourced code for 6.6 kernel: git clone https://github.com/minuscat/rpi-6.6.y.git

  3. Go into kernel directory: cd rpi-6.6.y/

  4. Review the url on building rpi kernels

  5. Set the KERNEL environment variable to a unique value (this is just an example): KERNEL=kernel_2712_l4s

  6. Make a Rpi5 config: make bcm2712_defconfig

  7. Set prague CCA & dual queue kernel flags: make menuconfig

  8. Set CONFIG_LOCALVERSION environment variable to a unique value: CONFIG_LOCALVERSION="-l4s-kernel"

  9. Compile kernel, modules, device tree blobs: make -j6 Image.gz modules dtbs

  10. Install modules: make -j6 modules_install

  11. sudo cp /boot/firmware/$KERNEL.img /boot/firmware/$KERNEL-backup.img sudo cp arch/arm64/boot/Image.gz /boot/firmware/$KERNEL.img sudo cp arch/arm64/boot/dts/broadcom/*.dtb /boot/firmware/ sudo cp arch/arm64/boot/dts/overlays/*.dtb* /boot/firmware/overlays/ sudo cp arch/arm64/boot/dts/overlays/README /boot/firmware/overlays/
    1. Checkout l4s branch

    1. Download bcm2711_defconfig from this site

    1. make menuconfig

    Install custom kernel

    1. make modules_install

    2. make install

    3. emacs /boot/config.txt

    4. kernel=vmlinuz-5.15.72-v8+

    5. # uncomment if you get no picture on HDMI for a default "safe" mode

      #hdmi_safe=1

    6. or sudo systemctl set-default multi-user.target

    7. reboot

    Verify TCP Prague and BBRv2

    rjmcmahon@raspberrypi:~ $ uname -r

    5.15.72-v8+

    kernel.random.entropy_avail = 256

    kernel.seccomp.actions_avail = kill_process kill_thread trap errno user_notif trace log allow

    net.ipv4.tcp_available_congestion_control = reno bbr bbr2 cubic dctcp vegas prague

    net.ipv4.tcp_available_ulp =


    Configuration for Testing
    You can configure the test machine with the following commands.


    Enabling Accurate ECN

    sysctl net.ipv4.tcp_ecn=3


    Enabling BBRv2 CC w/ Accurate ECN

    sysctl net.ipv4.tcp_ecn=3 net.ipv4.tcp_congestion_control=bbr2


    Enabling TCP Prague CC w/ Accurate ECN

    sysctl net.ipv4.tcp_ecn=3 net.ipv4.tcp_congestion_control=prague


    Enabling CUBIC CC w/ Accurate ECN

    sysctl net.ipv4.tcp_ecn=3 net.ipv4.tcp_congestion_control=cubic


    Enabling CUBIC CC w/o Accurate ECN

    sysctl net.ipv4.tcp_ecn= net.ipv4.tcp_congestion_control=cubic

    Build the latest iperf 2

    1. cd /usr/local/src

    2. git clone https://git.code.sf.net/p/iperf2/code iperf2-code

    3. cd iperf2-code

    4. .configure

    5. make -j 4

    6. make install

    Build goresponsiveness tool (git repo)

    wget https://go.dev/dl/go1.20.6.linux-arm64.tar.gz

    tar -C /usr/local/ -xvf go1.20.6.linux-arm64.tar.gz

    tar -C /usr/local -xzf go1.20.6.linux-arm64.tar.gz

    export PATH=$PATH:/usr/local/go/bit

    type go

    go version

    cd goresponsiveness/

    go mod download

    go build networkQuality.go



    TCP client stats

    Adding a realtime clock

    Example clone with dd (from micro SD to file, use lsblk to find device)

    [rjmcmahon@ryzen3950 L4S]$ sudo dd bs=4M if=/dev/sdc of=l4s_kernel conv=fsync

    [sudo] password for rjmcmahon:

    15226+1 records in

    15226+1 records out

    63864569856 bytes (64 GB, 59 GiB) copied, 692.6 s, 92.2 MB/s

    Example clone with dd (from file to micro SD, use lsblk to find device)



    Cross compile for a buildroot small embedded system (not done)

    Testing Notes


    A picture